The clearest illustration of economic inefficiency would be: (w) maintaining a warehouse full of pet rocks within hopes such that someday the fad will return. (x) pet rocks being unavailable to people willing to pay a price that exceeds the marginal social costs of producing them. (y) production and sale of pet rock food at high prices. (z) no one making or wanting to buy pet rocks.
How can I solve my economics problem? Please suggest me the correct answer.